In commonly assigned application 09/645,828 filed Aug. 25, 2000 and entitled GUSSETED ZIPPER BAG there is disclosed gusseted reclosable packaging wherein the gusset walls are captured between the mating profiles of a zipper. The wall portions that are captured by the zipper profiles are thinner than the main portions of the bag to facilitate the gussets being captured by the profiles and hence make such bags more compatible with barrier films. The present invention relates to an improved method for forming such gusseted reclosable packaging wherein both the bag sides and bottom are gusseted. The resultant bag may be filled in line with the bag formation process or individual bags may be filled.
The principal object of the present invention is to provide an improved method for manufacturing such bags in an efficient manner that readily lends itself to automated production.
The above and other objects and advantages are attained by providing first and second carrier webs with discrete, mating zipper profile sections. The zipper profile sections are separated from each other on the carrier web by zipper free sections of carrier web. The carrier webs are respectively attached to the tops of first and second bag wall films as the bag wall films are brought together. The bag wall films may be separate webs or a single, longitudinally folded web. The carrier webs are formed of thinner gauge plastic film than the bag wall films. The first and second bag wall films and first and second carrier webs are cross sealed with the carrier webs being sealed through the zipper free sections web and the assembly is cut transversely through the cross seals to form a bag. A bottom gusset is formed in the bag by reverse folding the bottom of the bag walls. If the bag walls were formed of separate films the films have to be connected either by simply sealing the bag wall film bottoms to each other or by sealing a folded bottom web to the bottoms of both bag wall films. Side gussets are then formed by pushing in the end parts of the bag walls as well as the zipper free sections of carrier web between the open zipper sections. If desired, a peel seal may be provided below the zipper profile sections to enable hermetic sealing of the bag contents and provide tamper resistance.
In a modification of the invention windows are cut in the bag wall films at the tops of the bag walls at locations that correspond to the side gussets. Rather than placing the carrier webs at the top edges of the bag films, the carrier webs are positioned on the bag wall films so that the profile free sections of carrier film cover the windows.